// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_AURA_ENV_H_
#define UI_AURA_ENV_H_

#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "base/observer_list.h"
#include "base/supports_user_data.h"
#include "ui/aura/aura_export.h"
#include "ui/events/event_handler.h"
#include "ui/events/event_target.h"
#include "ui/gfx/geometry/point.h"

namespace ui {
class ContextFactory;
class PlatformEventSource;
}
namespace aura {

namespace test {
    class EnvTestHelper;
}

class EnvObserver;
class InputStateLookup;
class Window;
class WindowTreeHost;

// A singleton object that tracks general state within Aura.
class AURA_EXPORT Env : public ui::EventTarget, public base::SupportsUserData {
public:
    // Creates the single Env instance (if it hasn't been created yet). If
    // |create_event_source| is true a PlatformEventSource is created.
    // TODO(sky): nuke |create_event_source|. Only necessary while mojo's
    // nativeviewportservice lives in the same process as the viewmanager.
    static void CreateInstance(bool create_event_source);
    static Env* GetInstance();
    static Env* GetInstanceDontCreate();
    static void DeleteInstance();

    void AddObserver(EnvObserver* observer);
    void RemoveObserver(EnvObserver* observer);

    int mouse_button_flags() const { return mouse_button_flags_; }
    void set_mouse_button_flags(int mouse_button_flags)
    {
        mouse_button_flags_ = mouse_button_flags;
    }
    // Returns true if a mouse button is down. This may query the native OS,
    // otherwise it uses |mouse_button_flags_|.
    bool IsMouseButtonDown() const;

    // Gets/sets the last mouse location seen in a mouse event in the screen
    // coordinates.
    const gfx::Point& last_mouse_location() const { return last_mouse_location_; }
    void set_last_mouse_location(const gfx::Point& last_mouse_location)
    {
        last_mouse_location_ = last_mouse_location;
    }

    // Whether any touch device is currently down.
    bool is_touch_down() const { return is_touch_down_; }
    void set_touch_down(bool value) { is_touch_down_ = value; }

    void set_context_factory(ui::ContextFactory* context_factory)
    {
        context_factory_ = context_factory;
    }
    ui::ContextFactory* context_factory() { return context_factory_; }

private:
    friend class test::EnvTestHelper;
    friend class Window;
    friend class WindowTreeHost;

    Env();
    ~Env() override;

    // See description of CreateInstance() for deatils of |create_event_source|.
    void Init(bool create_event_source);

    // Called by the Window when it is initialized. Notifies observers.
    void NotifyWindowInitialized(Window* window);

    // Called by the WindowTreeHost when it is initialized. Notifies observers.
    void NotifyHostInitialized(WindowTreeHost* host);

    // Invoked by WindowTreeHost when it is activated. Notifies observers.
    void NotifyHostActivated(WindowTreeHost* host);

    // Overridden from ui::EventTarget:
    bool CanAcceptEvent(const ui::Event& event) override;
    ui::EventTarget* GetParentTarget() override;
    scoped_ptr<ui::EventTargetIterator> GetChildIterator() const override;
    ui::EventTargeter* GetEventTargeter() override;

    base::ObserverList<EnvObserver> observers_;

    int mouse_button_flags_;
    // Location of last mouse event, in screen coordinates.
    gfx::Point last_mouse_location_;
    bool is_touch_down_;

    scoped_ptr<InputStateLookup> input_state_lookup_;
    scoped_ptr<ui::PlatformEventSource> event_source_;

    ui::ContextFactory* context_factory_;

    DISALLOW_COPY_AND_ASSIGN(Env);
};

} // namespace aura

#endif // UI_AURA_ENV_H_
